Electric switch



(No Model.) 3 Sheets-Sheet 1 L. DAPT.

ELEGTRIO SWITCH.

No. 322.915. Patented July 28, 1885.

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3 SheetsSheet 2.

(No Model.)

L. DAFT.

ELECTRIC SWITCH.

No. 322,915. Patented July 28, 1885.

(No Model.) 3 SheetsSheet 3.

LDAFT.

ELECTRIC SWITCH. No. 322,915. Patented July-28, 1885.

UNITED STATES PATENT OFFICE.

LEO DAFT, OF GREENVILLE, NE? JERSEY.

ELECTRlC SWITCH.

SPECIFICATION forming part of Letters Patent No. 322,915 dated .ll'uly28, 1885.

Application filed March 9, 1885. (No model.)

T 0 all whom it may concern:

Be it known that l, LEO DAFT, a subject of the Queen of Great Britain,residing at Greenville, in the county of Hudson and State of New Jersey,have invented a new and useful Improvement in Electric Switches, ofwhich the following is a full, true, and exact description, referencebeing had to the accompanying drawings.

The object of my invention is to provide a switch for electric motorsand electric-light currents which shall be capable of reversing thecurrent quickly and readily, and at the same time occasion acomparatively gradual weakening of the current to the point of actualcutting off, so as to prevent shock being communicated to any personholding both line wires or rails from secondary discharge. This result Iaccomplish by gradually throwing in a resistance to the point of cuttingout the current altogether, and gradually removing the same when thecurrent is to be thrown out.

My invention will be readily understood from the accompanying drawings,in which Figure 1 represents an external elevation of my improvedswitch; Fig. 2, a vertical section through the case, showing aperspective View of part of my contrivance; Fig. 3, a plan andperspective view of the apparatus with the case broken away; Fig. 4, avertical section through Fig. 1; Fig. 5, a view of a modification of myapparatus where reversal of the current is not desired; Fig. 6, a detailview of the method of arranging my resistances; Fig. 7, a view of acondenser, which I may use under certain circumstances.

My switch consists, generally, of acylinder, 0, provided withsymmetrical plates D D, above and below. On the left of the apparatus,as shown in'Fig. 3, these plates have a straight edge, and on the rightthe edge presented to the conducting-switches, to be described, isangular, although, if preferred, both edges might be made angular. The

spring or springs E are provided on the left of the apparatus, whichnormally rest on the insulating-surface of the switch between the platesD D, as shown in Fig. 4. On the right six springs, 1 2 8 4 5 6, areshown, which normally rest upon the insulating material.

the base of the box, or any other convenient location.is arranged arheostat or series of resistances, B. As shown, the said rheostat isrepresented as a carbon rheostat; but other suitable structures might beemployed. A laminated carbon rheostat may be employed composed of anumber of pieces of carbon plate having at intervals conductingsurfacesinserted so as to get practically a carbon rheostat of varyingresistance, such variations to be determined at will according to'themnumber of laminze interposed between each conducting -surface. Insome cases I prefer to use a solid cake of carbon or other suitablematerial,into which are placed in process of manufacture suchconducting-surfaces, which I vary in superficial area according to thedegree of resistance which I wish to employ. Suitable pigments havingalow degree of conductivity may be used for this purpose; but Ipreferably employ compounds of carbon with silicate of magnesia for thehigher resistance, and a compound of carbon and the golden sulphuret ofantimony for lower resistances, and I vary these compounds according tothe character of the current which I am employing.

By referring to Fig. 6 it will be observed that the laminated carbonresistances are arranged in a frame-work with adjustable screws ateither end, so as to permit of a varying pressure being put upon theplates. The object of this is to admit of an almost infinite variationof resistance in the same rheostat by varying the pressure.

The method of connecting up my reversingswitch will be readilyunderstood from Fig. 4. Supposing M to represent a motor the movement ofwhich it is desired to reverse, and that the current to be reversed'isreceived on the wires a and b, we will assume that the crank D,controlling cylindrical-switch E, I

IOO

thus connected with spring 6 is connected with one of the terminals ofthe field-of-force magnets. Now, as the handle D is swung upward, thespring 6 will pass uponthe insulating surface,when the current will becompelled to travel through the last section of the rheo' stat, andthence by wire 5 to spring 5, bearing upon the plate D. As the motioncontinues the sections of the rheostat will be one after the otherthrown into circuit, increasing the resistance until the last spring, 1,leaves the conducting-plate D. If entire absence of all residualdischarge is required, an ordinary condensersuch as is shown in Fig.7may be connected between the wires a and b,- but in most cases this isunneccessary. As the crank Bis continued to be swung toward the stop 1?,the spring 1 will press upon the angular surface of D, and the motion ofthe motor M will be thereby reversed,the relation of the brushes to thecurrent having been reversed in the switch. As the motion of the crank Dcontinues, one after the other of the sections of the rheostat R will bethrown out, until the spring 6, connected with the wire 6, bears uponthe plate D,when all artificial resistance will be removed from thecircuit.

In Fig. 5 the same arrangement is shown applicable to a switch, which isused where it is not desired to reverse the circuit. A single plate, D,and a single set of springs will only be required in this instance.

hat I claim as my invention, and desire to secure by Letters Patent, is-

1. The combination of a cylindrical switch,

provided with an angular conducting-plate embedded in insulatingmaterial, with aseries of springs connected to successive sections of aresistancecoil, and adapted to be successively brought in contact withthe angular edge of the conducting-plate, thereby gradually increasingor decreasing the resistance of the circuit, substantially as described.

2. The combination of a reversing-switch, having contact-plates and aseries of springs arranged to connect therewith, a series ofresistances, and the connection shown, whereby the current may bereversed in the switch, and the series of resistances simultaneouslythrown into or out of circuit, thereby accomplishing the double resultof reversing the current and avoiding secondary discharge, substantiallyas described.

3. The combination of the reversing-switch C, provided with angularplates D D, with a series of springs adapted to bear against said platesand connected in succession to a series of resistances for the purposeof reversing the current and preventing secondary discharge,substantially as described.

4. The combination of the switch 0, provided with plate D, and theseries of springs, l 2 3 4 5 6, with an adjustable rheostat connected tosaid springs, substantially as described.

LEO DAFT.

Witnesses:

Gno. H. EVANS, WM. A. PoLLooK.

